1. Field of the Invention
This invention relates to an urethane modified epoxy resin and a highly water-proof, chemical-proof and adhesive resin composition to be suitably used as an adhesive agent and, more particularly, it relates to a resin composition that can be suitably used as an adhesive agent for iron and non-ferrous metals such as aluminum, zinc, copper and other transition metals and provides, when set, an excellent bonding strength in terms of shearing strength and peeling strength and the like.
2. Description of Relating Art
Epoxy resin type adhesive agents are known to be highly effective for bonding metals, glass, concrete, stones and other objects. On the other hand, as they find a broader scope of application in recent years, more and more rigorous requirements are posed on them in terms of peeling strength, shearing strength, thermoresistant adhesive property, water resistant adhesive property, creep characteristics, durability and the like.
While epoxy resin generally shows a relatively high shearing strength, it does not provide a satisfactory level of peeling strength and flexibility required for structures. In order for epoxy resin to operate more satisfactory, therefore, thermoplastic resin is normally added to it so that they are chemically combined to give rise to a reaction product or simply blended to produce an alloy.
For example, Japanese Patent Application Opened No. 61-228015 discloses an urethane modified epoxy resin obtained by chemically reacting of an urethane-prepolymer produced from a polyhydroxyl compound and a polyisocyanate compound with an epoxy resin.
Japanese Patent Application Opened No. 62-53527 teaches another urethane modified epoxy resin obtained by chemically reacting of an urethane-prepolymer produced from high and low molecular weight polyhydroxyl compounds and a polyisocyanate compound with a compound containing epoxy and hydroxyl groups.
Japanese Patent Application Opened No. 58-63758 discloses a condensation product of epoxy resin and phosphoric acid or a phosphate.
While the above cited urethane modified epoxy resins may show an appropriate level of flexibility and be highly effective for bonding steel plates, they do not operate satisfactorily for bonding non-ferrous metals. Although phosphorus epoxy resin products are effective for bonding non-ferrous metals such as zinc-plated steel plates, aluminum and stainless steel, their shearing strength and peeling strength are very poor and far from satisfactory.
Therefore, it is the object of the present invention to provide an adhesive epoxy resin composition that operates satisfactorily as an adhesive agent for non-ferrous metals, showing an excellent level of shearing strength and peeling strength.